Cyclone furnaces



Nov. 21, 1961 o. LOTZ Re. 25,086

CYCLONE FURNACES Original Filed May 23, 1955 2 Sheets-Sheet 1 FIG. 1 2

INVENTOR.

OTTO LOTZ ATTORNEY Nov. 21, 1961 0., LOTZ Re. 25,086

CYCLONE FURNACES Original Filed May 23, 1955 2 Sheets-Sheet 2 FIG. 2

INVENTOR.

OT TO LOTZ United Stat s Patent 25,086 CYCLONE FURNACES Otto Lotz,Oberhausen, Rhineland, Germany, assignor to The Babcock 8: WilcoxCompany, New York, N.Y., a corporation of New Jersey Original No.2,957,436, dated Oct. 25, 1960, Ser. No. 510,332, May 23, 1955.Application for reissue Dec. 7, 1960, Ser. No. 75,049 In Germany Apr. 9,1949,

Public Law 619, Aug. 23, 1954 Patent expires Apr. 9, 1969 9 Claims. (Cl.110-48) Matter enclosed in heavy brackets appears in the original patentbut forms no part of this reissue specification; matter printed initalics indicates the additions made by reissue.

The present invention relates to the'construction and operation ofcyclone furnaces for burning particle-form slag-forming solid fuel atfurnace chamber temperatures above the ash fusion temperature to therebypermit the removal of the inco-rnbustible ash residue from the furnacechamber as a liquid slag, and more particularly to furnaces of thecharacter described in which the gaseous products of combustion aredischarged from the furnace chamber through a restricted gas outlet.

The granular fuels normally used in such furnaces have particle sizes ofand under, and contain as a result of the fuel crushing operation aproportion of dustlike particles, known as fines. The fuel and airmixture is introduced in the combustion chamber through a tangentialinlet arranged to effect a whirling motion of the fuel and air mixturein a helical path axially of and toward the opposite end of the furnace.In operation the entering fuel and air stream is rapidly ignited and thecentrifugal effect of the whirling stream causes the ash particlesreleased from the burning fuel particles to deposit in a moltencondition on the furnace wall and form a film or layer of molten slagthereon on which the larger fuel particles are caught and burned inplace.

If the super-atmospheric pressure of the air supply to a cyclone furnacewere a few tenths of an inch of water, the column of fuel in the fuelsupply duct leading to the cyclone furnace would generally serve to sealthe duct. Actually, however, a cyclone furnace is operated withpreheated combustion air supplied at high pressure, which may amount to20 to 80 inches of water, according to the load. At such pressures greatdifficulty arises in providing a reliable seal and fuel ignition in thebunker may be caused by infiltration of the hot high pressure air.

The present invention avoids the foregoing difficulty by providingsealing means which effectively check infiltration of the hot highpressure combustion air into the fuel bunker. In particular, the presentinvention provides combustion air supply means including an air duct ofconverging cross-section disposed substantially tangentially withrespect to means forming a fuel and combustion air whirl chamber and afuel supply duct arranged for the gravitational introduction ofparticle-form slagforming fuel into the air duct and opening into theconverging portion of the air duct, preferably at an acute angle to theaxis of flow and at the narrowest crosssection thereof. The air duct isconvergently arranged in order to decrease the pressure of the airflowing therethrough and thereby transform some of its static pressureinto velocity pressure, preferably reaching a minimum static pressurevalue at the fuel supply duct opening into the air duct. As the airpasses the fuel supply opening, a suctionis produced in' the fuel supplyduct, i.e., the static pressure in the air supply duct at a locationadjacent the fuel supply opening is less than the pressureprevailin'g'in the fuel supply duct or the pressure applied to the fuelReissued Nov. 21, 1961 duct is limited to a relatively small value, thuspreventing or limiting the discharge of air into the fuel bunker.

The various features of novelty which characterize my invention arepointed out with particularity in the claims annexed to and forming apart of this specification. lfor a better understanding of theinvention, its operating advantages and specific objects attained by itsuse, reference should be had to the accompanying drawings anddescriptive matter in which I have illustrated and described a preferredembodiment of my invention.

Of the drawings:

FIG. 1 is a somewhat diagrammatic sectional elevation of a horizontallyarranged cyclone furnace constructed in accordance with my invention,and the adjacent portion of an associated water tube steam boiler;

FIG. 2 is a sectional front elevation of a burner 01 I the cyclonefurnace taken on the line 2-2 of FIG. 1

and

FIG. 3 is a fragmentary sectional front elevation of cyclone furnacetaken on the line 3-3 of FIG. 1.

In FIG. 1, the raw fuel is supplied from a bunker 2 through a slidevalve 4 for shutting off the fuel and a due 6 to a feeder 8, which feedsthe fuel to a crusher 10 dis charging to a fuel supply duct 12. Thelower part of th fuel supply duct 12 is formed as a nozzle shaped fuesupply means for the burner 14 and the duct 12 and primary air supplyduct 16, the end of which is forme as a nozzle shaped air supply meansfor the burner, cor verge to a confluence, the fuel supply means and theai supply means being relatively arranged to have the a5 supply ductexert an ejector effect on the lower end the fuel supply duct. Thenozzle shaped end of the du 16, is tangentially disposed in relation tothe scroll shape peripheral wall of a whirl chamber forming part of, ti.burner 14-. A sliding plate 18 forming a division wall b1 tween the fuelsupply duct 12 and the primary air supp? duct 16 may be moved upwardlyor downwardly in 0rd to regulate the ejector or suction effect on thefuel suppj duct.

Outwardly of and co-axial, and in communication wit the whirl chamber ofthe burner 14 is an auxiliary whi chamber 19 of relatively smalldiameter fitted at its out end with an inspection port. Openingtangentially in the auxiliary whirl chamber 19 is an air duct 20. The asupplied through the duct 20 serves to create a parti vacuum, whichenables the inspection port to be openl without the discharge of flameor hot gases through tl port.

The substantially cylindrical, refractory walled C0] bustion chamber 22is formed with 'a co-axial outward flaring gas outletthroat 24 leadingto a boiler radiatit space 26, towards which the combustion chamberdownwardly inclined at a small angle-towards a sl opening 28.

A secondary air duct 30 connects with nozzles 32 co: municatingtangentially with the com-bustion chamber as shown in FIG. 3. Thenozzles 32 and auxiliary f1 inlets 34 are also arranged after the mannerof an eject the auxiliary fuel inlets 34 preferably having an axis flowforming an acute angle with the axis of flow of 1 nozzles 32 and beingdisposed radially outwards w respect to the nozzles 32 and slightlyforward thereof the direction of whirl. The nozzles 32 are introducedtween the ends of circularly bent cooling tube leng surrounding thecombustion chamber and the auxili: fuel inlets 34 are introduced betweenthe neighbor tube lengths.

is supplied through the primary air duct 16. As the 1 ary air flowsthrough the converging portion of the 1r duct 16, its velocity pressureincreases and its static ressure decreases. The fuel supply duct 12opening no the primary air duct 16 is preferably located at the arrowesteross-section thereof where the primary air 5 atm pressure is at aminimum. With this arrangement, to low primary air static pressureadjacent the fuel suply duct opening causes a suction to be created inthe 1el supply duct 12 or the pressure applied to the duct 2 is limitedto a relatively small value.

The scroll shaped surface of the burner 14 causes the fimary air andfuel mixture to rotate, with the result at it enters the combustionchamber with a strong whirl 1d moves helically along its peripheral wallwhile comlstion takes place. Secondary air is supplied through e nozzles32. The hot gases pass through the outlet roat 24 to the radiation space26 and the molten slag ns down the walls of the combustion chamber andIt of the slag opening 28. In order to start up or to maintain thecyclone furnace partial load, suitable fuel more readily ignited andirned than granular fuel may be supplied to the nozzles Thus combustiblegas, or a mixture of pulverized el and air may be supplied to thenozzles 34. During :h operation, the air stream from the nozzles 32tends press the fuel streams from the nozzles 34 against the :ractorywall of the combustion chamber, so that the 11 is strongly heated. Theair issuing from the nozzles moreover, exerts a. suction effect in thenozzles 34. the secondary air enters the converging section of :t 32,its velocity pressure begins to increase, reaching maximum value at theair inlet to the combustion lmber 22. The action of the high velocitysecondary adjacent the auxiliary fuel nozzles 34 creates a low ticpressure at this location and thus reduces considbly the combustionchamber pressure head that must overcome by auxiliary fuel deliveryequipment. f desired, nozzles 34 may also be used in continuous :rationfor working with fine particles such as fly ash grits, from fuelsupplied to another furnace or other naces, the slag'from the particlesbeing deposited in [ten form on the wall of the combustion chamber 22 :ethe mean average temperature in the chamber is mally above the fuel ashfusion temperature. Vhile in accordance wit-h the provisions of thestatutes ave illustrated and described herein the best form of inventionnow known to me, those skilled in the will understand that changes maybe made in the n of the aparatus disclosed without departing from spiritof the invention covered by my claims, and that ain features of myinvention may sometimes be used advantage without a corresponding use ofother ures. hat is claimed is: I The process of burning and melting flyash which prises introducing a stream of air and slag-forming icle fuelin suspension at a high .velocity into a coma ion chamber ofsubstantially circular cross-section s to move at a high velocity alongthe circumferential thereof, introducing a stream of fly ash into saidbustion chamber so as to'move in a whirling path avel along and adjacentto the circumferential wall :of while maintaining a normal meantemperature e chamber above the fuel ash and fly ash fusion temtures,causing the fuel and air and fly ash so introd to move axially of thecombustion chamber rds the gas discharge end thereof through a helicalof travel along the circumferential wall of the comon chamber ofsufiicient length to cause combustion 1e fuel and the release of fuelash in a condition to a sticky surface on the circumferential wall towhich particles and fly ash particles adhere and are scrubbed 1ecombustion gases, causing the furnace gases to rage from said end of thecombustion chamber, and :ting and withdrawing the ash separated in thecombustion chamber and fly ash in a molten condition from the lower partof the chamber.

2. The process of burning and melting fly ash which comprisesintroducing a stream of air and slag-forming particle fuel in suspensionat a high velocity into a combustion chamber of substantially circularcross-section so as to move at a high velocity along the circumferentialwall thereof, introducing a stream of fly ash tangentially into saidcombustion chamber so as to move in a whirling path of travel along andadjacent to the circumferential wall thereof while maintaining a normalmean temperature in the chamber above the fuel ash and fly ash fusiontemperatures, causing the fuel and air and fly ash so introduced to moveaxially of the combustion chamber towards the gas discharge end thereofthrough a helical path of travel along the circumferential wall of thecombustion chamber of suflicient length to cause combustion of the fueland the release of fuel ash in a condition to form a sticky surface onthe circumferential wall to which fuel particles and fly ash particlesadhere and are scrubbed by the combustion gases, causing the furnacegases to be deflected at the gas discharge end of the combustion chamberinwardly towards the axis of the chamber and to discharge from said endof the combustion chamber at a high velocity, and collecting andwithdrawing the ash separated in the combustion chamber and fly ash in amolten condition from the lower part of the chamber adjacent the gasoutlet.

3. The process of burning and melting fly ash which comprisesintroducing a stream of air and slag-forming particle fuel in suspensionat a high velocity into one end of a combustion chamber of substantiallycircular cross-section arranged with its axis substantially horizontal,introducing a stream of fly ash into said combustion chambertangentially to the circumferential wall thereof so as to move in a'whirling path of travel along and adjacent to the circumferential wallwhile maintaining a normal mean temperature in the chamber above thefuel ash and fly ash fusion temperatures, causing the fuel and air andfly ash so introduced to move axially of the combustion chamber towardsthe gas dischargeend thereof through a helical path of travel along thecircumferential wall of the combustion chamber; of suflicient length tocause combustion of the fuel. and the release of fuel ash in a conditionto form a sticky surface on the circumferential wall to which fuelparticles and fly ash particles adhere and are scrubbed by thecombustion gases, causing the furnace gases to discharge from said endof the combustion chamber, and collecting and withdrawing the, ashseparated inthe combustion chamber and fly ash in a molten conditionfrom the lower part of the chamber adjacent the gas outlet.

4. A cyclone furnace having walls including fluid cooled tubes forming acombustion chamber of substantially circular cross-section, meansforming a restricted gas outlet at one end of said combustion chamber,means for introducing a whirling stream of combustion air andslag-forming particle fuel in suspension at a high velocity into saidcombustion chamber and effecting a helical path of travel therein alongthe circumferential wall of said combustion chamber, said last namedmeans including an air supply duct and a fuel supply duct disposedoutwardly of said air duct and arrangedfor the gravitationalintroduction of slag forming particle fuel into said air supply duct,said air duct having a discharge portion of gradually decreasingcross-sectional area in the direction of flow arranged with its axis offlow at a sharply acute angle to the axis of flow of said fuel duct andopening to the discharge end of said fuel duct to exert an ejectoreffect on said fuel duct andthereby minimize the back pressure on thefuel duct, and a slidable plate forming a common wall between said fuelduct and air duct and movable to regulate the suction effect of the highvelocity air flowing through said air-duct on said fuel duct. I

5. A cyclone furnace having walls including fluid cooled tubes forming acombustion chamber of substantially circular cross-section, meansforming a restricted gas outlet at one end of said combustion chamber,means forming a fuel and combustion air whirl chamber of smallercross-sectional area than and opening to the opposite end of saidchamber, and means for introducing a whirling stream of combustion airand slag-forming particle fuel in suspension at a high velocity intosaid whirl chamber and effecting a helical path of travel therein andalong the circumferential wall of said combustion chamber, said glastnamed means including an air supply duct opening tangentially into saidwhirl chamber and a fuel supply duct disposed outwardly of said air ductand arranged for the gravitational introduction of slagforming particlefuel into said air supply duct, said air duct having a discharge portionof gradually decreasing cross-sectional area in'the direction of flowarranged with its axis of flow at a sharply acute angle to the axis offlow of said fuel duct and opening at its minimum cross-section to thedischarge end of said fuel duct to exert an ejector effect on said fuelduct and thereby minimize the back pressure on the fuel duct, and aslidable plate forming a common wall between said fuel duct and air ductand movable to regulate the suction effect of the high velocity airflowing through said air duct on said fuel duct.

6. A cyclone furnace comprising wall means forming an elongatedcombustion chamber of circular transverse cross-section having a gasoutlet throat in one end thereof, means forming a fuel and primary airwhirl chamber of smaller diameter than and opening into the other end ofsaid combustion chamber, primary air supply means including an air ductof converging cross-section in the direction of flow for increasing thevelocity of the air disposed substantially tangentially with respect tosaid whirl chamber, a fuel supply duct disposed outwardly of and openingto the converging portion of said primary air duct and arranged for thegravitational introduction of particle-form-slag-forming fuel into saidprimary air duct, said fuel supply duct having an axis of flow formingan acute angle with the axis of flow of the converging portion of saidprimary air duct, a vertically slidable plate forming a common inclinedwall between said fuel supply duct and said primary air duct and movableto regulate the suction effect of the high velocity primary air on saidfuel supply duct, a series of convergent type secondary air supplynozzles arranged to tangentially introduce streams of secondarycombustion air into said combustion chamber at a location between saidwhirl chamber and said gas outlet, auxiliary fuel inlets disposedoutwardly of and open-ing to said secondary air supply nozzles adjacentsaid combustion chamber, said auxiliary fuel inlets having an axis offlow forming an acute angle with the axis of flow of said secondary airsupply nozzles.

7. A cyclone furnace comprising wall means forming an elongatedcombustion chamber of circular transverse cross-section having a gasoutlet throat in one end thereof, means forming a fuel and primary airwhirl chamber of smaller diameter than and opening into the other end ofsaid combustion chamber, primary air supply means including an air ductof converging cross-section in the direction of flow for increasing thevelocity of the air disposed substantially tangentially with respect tosaid whirl chamber, a fuel supply duct disposed outwardly of and openingto the converging portion of said primary air duct at the narrowestcross-section thereof and arranged for the gravitational introduction ofparticleform slag-forming fuel into said primary air duct, said fuelsupply duct having an axis of flow forming an acute angle with the axisof flow of the converging portion of said primary air duct, a verticallyslidable plate forming a common inclined wall between said fuel supplyduct and said primary air duct and movable to regulate the suctioneffect of the high velocity primary air on said fuel supply duct, aseries of convergent type secondary air supply nozzles arranged totangentially introduce streams of secondary combustion air into saidcombustion chamber at a location between said whirl chamber and said gasoutlet, auxiliary fuel inlets disposed outwardly of and opening to saidsecondary air supply nozzles at the narrowest cross-section thereof andabutting said combustion chamber, said auxiliary fuel inlets having anaxis of flow forming an acute angle with the axis of flow of saidsecondary air supply nozzles and being disposed radially outward withrespect to said secondary air supply nozzles.

'8. The process of burning and melting fly ash which comprisesintroducing a stream of air and slag-forming particle fuel in suspensionat a high velocity into a combustion chamber of generally symmetricalformation about a central longitudinal axis so as to move in a whirlingpath of travel through said chamber, introducing a stream of gas-bornefly ash into said combustion chamber so as to move in a whirling path oftravel along and adjacent to the boundary surface thereof whilemaintaining a normal mean temperature in the chamber above the fuel ashand fly ash fusion temperatures, causing the fuel and air and fly ash sointroduced to move axially of the combustion chamber towards the gasdischarge end thereof through a helical path of travel along theboundary surface of the combustion chamber of sufficient length to causecombustion of the fuel and the release of fuel ash in a moltencondition, causing the furnace gases to discharge from said end of thecombustion chamber, and collecting and withdrawing the ash separated inthe combustion chamber and fly ash in a molten condition from the lowerpart of the chamber.

9. The process of burning and melting fly ash which comprisesintroducing a stream of air and slag-forming particle fuel in suspensionat a high velocity into a combustion chamber of generally symmetricalformation about a central longitudinal axis so as to move in a whirlingpath of travel through said chamber, introducing a stream of gas-bornefly ash into said combustion cham ber so as to move in a whirling pathof travel through said chamber while maintaining a normal meantemperature in the chamber above the fuel ash and fly ash fusiontemperatures, with the whirling stream of fly ash being further removedfrom the axis of said chamber than the whirling stream of. fuel and airat their respective positions of introduction into said chamber, causingthe fuel and air and fly ash so introduced to move axially of thecombustion chamber towards the gas discharge end thereof through ahelical path of travel along the boundary surface of the combustionchamber of suflicient length to cause combustion of the fuel and therelease of fuel ash in a molten condition, causing the furnace gases todischarge from said end of the combustion chamber, and collecting andwithdrawing the ash separated in the combustion chamber and fly ash in amolten condition from the lower part of the chamber.

References Cited in the file of this patent or the origlnal patentUNITED STATES PATENTS 1,535,903 Bollins Apr. 25, 1925 2,357,301 Baileyet al. Sept. 5, 1944 2,357,302 Kerr et al. Sept. 5, 1944 2,357,303 Kerret al. Sept. 5, 1944 2,361,681 Gordon Oct. 31, 1944 2,446,968 Toner Aug.10, 1948 2,483,728 Glaeser Oct. 4, 1949 2,652,011 Van Ramshorst :Sept.15, 1953 FOREIGN PATENTS 1,025,395 France Ian. 21, 1953 627,759 GermanyMar. 23, 1936

